There are conventional methods of generating pressure for fluid transportation in a micropump mechanism. For example, as shown in Japanese Laid-Opened Utilities Nos. 61180/1991 and 137582/1990, and Japanese Laid-Opened Patent No. 242266/1988, one of the methods is such that a vibrator is provided in a cavity, and the vibration of the vibrator is caused by means of the elasticity of a piezoelectric element or revolution control of a motor to generate pressure for transporting fluid. Japanese Laid-Opened Patent No. 126387/1986 and Japanese Patent No. 32231/1982 disclose another method for generating pressure by changing the volume of the cavity itself using the elasticity of the piezoelectric element.
The above conventional methods have large restrictions in order to miniaturize, lighten and reduce electric power of the pump mechanism because mechanical motion by the mechanism elements is the pressure source in the above conventional methods. More specifically, the displacement of the vibrator to an extent larger than a certain quantity is required to transport a desired quantity of fluid. Therefore the vibrator has to be large in order to obtain such a large displacement, and a good deal of energy is needed to effect displacement of the vibrator. Further, the pump mechanism itself is complicated because it includes a moving portion. As stated above, the conventional methods have trouble in miniaturizing, lightening and controlling precisely and in saving electricity of the pump mechanism.